Owning LSD became a crime in California on October 6, 1966, when a law signed by Governor Edmund Brown earlier that year took effect. It was the first ban. Other states copied it. Within two years most other states had copied it, and in 1968 the federal government made having it a national offence, then placed the drug in the tightest schedule of the Controlled Substances Act of 1970.
The drug had been studied in clinics and hospitals for about twenty years before it reached the street, and by the time California acted there were psychiatrists in several countries giving it to patients as an aid to therapy and a few researchers who thought it might mimic psychosis. Albert Hofmann had first made it at the Sandoz laboratories in Basel in 1938 and had discovered what it did five years later by accident. Sandoz supplied it to researchers under the name Delysid, suggesting doses for use in analysis.
What changed in the early 1960s was that supply got out of the clinic. Supply got out. Sandoz's patent ran out, informal production began on the west coast, and Timothy Leary, dismissed from Harvard in 1963, told a growing audience to try it. State governments were dealing with something they had no category for: a substance that had been legitimate medicine a few years earlier and was now being sold in tablet form at music venues. The California law made it a misdemeanour, and the penalties rose steeply in later revisions.
The effect on research was immediate. Grant money dried up. Hospital supplies were recalled, and the trials that had been running in Canada, Britain and the United States were wound down over the next few years. Research stopped. Human studies with the drug almost ceased for about three decades. They began again in small university programmes around 2006, and there are now licensed trials of LSD and related compounds at several medical schools, which was not something the legislators of 1966 had in mind.